This invention relates to semiconductor processing methods of forming an oxynitride film (SiOxNy) on a silicon substrate.
Semiconductor processing almost always involves growing some type of film on a substrate. One type of film is a dielectric film. Dielectric films are useful when integrated circuit elements, such as capacitors, are desired to be formed. One type of integrated circuitry which utilizes capacitors is integrated memory circuitry such as dynamic random access memories or memory arrays (DRAMs).
A material which is useful as a dielectric film is SiOx (predominately SiO2) which can be grown upon a silicon substrate. Such dielectric films can be grown by exposing a silicon substrate to an oxidizing agent under temperature and pressure conditions which are effective to grow such films. Such exposing may take place in a chemical vapor deposition (CVD) reactor. One prior art oxidizing agent for producing SiOx is N2O. Another useful dielectric material is oxynitride. Such is typically represented by the formula SiOxNy, where xe2x80x9cxxe2x80x9d equals 1 and xe2x80x9cyxe2x80x9d equals 1. N2O has also been used in the prior art as an oxidant for producing oxynitride films. Oxynitride films grown using N2O and other gases can form as a composite of an oxynitride layer and overlying silicon dioxide layer.
Unfortunately, the oxynitride layer results in a self-limiting growth process which typically limits the desired thickness of the finished layer. Such results from the oxynitride layer blocking diffusion of the reactant species to the silicon substrate interface where the reaction predominately occurs.
It would be desirable to develop improved methods of producing oxynitride dielectric layers that enhance at least one of the resultant desired thickness or growth rate.
A semiconductor processing method comprises forming an oxynitride film on a substrate. In accordance with a preferred aspect, a substrate having an exposed silicon surface is placed in a reactor. Subsequently, nitrogen, oxygen and fluorine gases are combined in the reactor under conditions which are effective to grow an oxynitride film on the exposed silicon surface. According to one preferred implementation, the nitrogen and oxygen gases are provided in the reactor from decomposition of a compound containing atomic nitrogen and oxygen. According to another preferred implementation, separate nitrogen, oxygen and fluorine source gases are fed into the reactor. In accordance with another preferred aspect, the substrate is exposed to rapid thermal processing conditions which are effective to grow an oxynitride film on an exposed silicon surface. In accordance with yet another aspect of the invention, a dielectric composite film is formed on an exposed silicon surface by combining nitrogen, oxygen, and fluorine in gaseous form in a reactor under temperature and pressure conditions, effective to grow a dielectric composite film which includes a first oxynitride layer proximate the silicon surface, and a second layer atop the first layer comprising SiOx.